番茄社区

"Medical Journeys" is a set of clinical resources reviewed by physicians, meant for the medical team as well as the patients they serve. Each episode of this 12-part journey through a disease state contains both a physician guide and a downloadable/printable patient resource. "Medical Journeys" chart a path each step of the way for physicians and patients and provide continual resources and support, as the caregiver team navigates the course of a disease.

Determining whether a patient has ulcerative colitis (UC) is not a simple matter. Symptoms are similar to a number of other conditions whose treatment is radically different, and the physician must sort through them and conduct a series of exams to narrow the possibilities.

Symptoms of Ulcerative Colitis

The following symptoms are most characteristic of UC and are most often what bring patients to seek medical care:

• Frequent loose and urgent bowel movements over a significant period of time

• Blood in the stool

• Cramping and abdominal pain

• Tenesmus

Over time, patients may also experience extra-intestinal or systemic symptoms such as weight loss, fever, dermatitis, and arthralgia. Tenesmus is the feeling of incomplete fecal evacuation and some patients will describe the symptom as constipation. One should suspect tenesmus if the patient says constipation but is going to the bathroom many times during the day.

The diagnostic challenge is that other forms of inflammatory bowel disease, particularly microscopic colitis and Crohn's disease, are marked by similar symptoms, as well as irritable bowel syndrome (IBS). Infections, most especially Clostridioides difficile, can also produce these symptoms.

Diagnostic Tests for Ulcerative Colitis

is the first order of business, although, ironically, a positive finding does not necessarily rule out UC -- infections are a potential complication in UC. Blood tests are helpful in this regard, as blood cell counts can indicate active infection, which need immediate treatment if detected.

Checking for anemia, which may result from UC-triggered rectal bleeding, is also part of the standard testing regimen. Blood tests for renal or hepatic abnormalities are also part of the standard workup, as are tests for generalized inflammation such as the erythrocyte sedimentation rate and C-reactive protein.

Stool tests are vital as well, to check for parasitic and bacterial infection. As well, biomarkers, including calprotectin and lactoferrin, can signal mucosal inflammation, one of the main pathological features of UC.

Noninvasive imaging may be performed supplemental to endoscopy to evaluate for other causes of abdominal pain and fever, such as diverticulitis. CT scans do provide adequate resolution to identify ulceration and disease-related morphology, but are not yet considered a full substitute for colonoscopy or sigmoidoscopy.

Other Risk Factors to Consider

The next installment in this series will examine UC risk factors in more detail, but it's important to take them into account during the diagnostic process, to raise or diminish suspicion.

The most significant by far is family history, which increases the risk (relative to the general population) by up to five-fold. However, genetic testing is not generally called for in routine practice, as there is no single gene variant or set of variants clearly associated with UC.

Additional potential risk factors include a history of high-fat diets, use of nonsteroidal anti-inflammatory drugs, Ashkenazi Jewish ancestry, and -- mysteriously and counterintuitively -- . The contribution of these factors to UC risk is low, however, compared with family history. Confirmed UC among first-degree relatives especially should raise the index of suspicion to a high level in patients with symptoms characteristic of the disorder.

Differential Diagnosis of Ulcerative Colitis

The tests listed above, along with the pattern of symptoms, will aid in distinguishing UC from Crohn's disease, microscopic colitis, irritable bowel syndrome with diarrhea (IBS-D), and other potential diagnoses.

UC and Crohn's disease are indistinguishable by symptoms alone. Crohn's disease is more associated with specific complications such as perianal fistula and intestinal strictures. In microscopic colitis, meanwhile, there is no bleeding, and even colonoscopy shows no visible abnormalities -- the disease is detected only via biopsy and histologic analysis.

IBS-D can be diagnosed using specified criteria (Rome Criteria); however, ongoing diarrhea often requires a colonoscopy to rule out an inflammatory condition. In addition to the frequent, urgent, loose stools, common features include rectal bleeding, anemia, and abdominal pain. The epidemiology is similar as well, with symptom onset most often in younger people. (There is also a constipation-predominant form of IBS that does not resemble UC.)

Ultimately, endoscopy -- colonoscopy -- is the most definite route to a final diagnosis.

Endoscopy to Diagnose Ulcerative Colitis

Visualizing the interior of the colon is the gold standard for diagnosing UC. If ulceration is present, it will be seen immediately. Endoscopy will also pick out the loss of haustra -- the small constrictions that give the normal colon its segmented look -- sometimes called the

At the same time, colonoscopy will confirm that the colonic lumen is not significantly restricted and that inflammation occurs in a single continuous area beginning in the rectum, which are other standard features of UC. Affected areas will typically be erythematous.

Endoscopic findings in Crohn's disease may be quite different. Ulcers may be present, but their appearance differs significantly from those in UC. Inflammation in Crohn's is patchy; it may occur anywhere in the colon and even extend into the small intestine. Moreover, the intestines may develop narrowing (strictures) in Crohn's disease and the mucosa develops a lumpy "cobblestone" appearance.

Another important function for endoscopy is to determine disease severity. Treatment for disease classified as mild differs considerably from that for moderate to severe UC. (Future installments in this series will address therapy).

Read Part 1 of this series: UC: Understanding the Epidemiology and Pathophysiology.

Up next: A deeper look at pathogenesis and risk factors